From: Wietse Venema (wietseporcupine.org)
Date: Wed Mar 04 2009 - 16:44:14 CST

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Santiago Romero:
> Wietse Venema escribi?:
> > Santiago Romero:
> >
> >> I case it happens again ... Where or what should I take a look? At OS
> >> level (disk or network I/O, processes...) I didn't see anything before
> >> the "postfix restart"...
> >>
> >
> > Try ``strace -o filename -p pid'' or the equivalent for your OS.
> >
>
> Hi.
>
> Today happened again in 2 new machines. The last one:
>
>
> top - 09:44:25 up 19:39, 2 users, load average: 4.68, 4.87, 4.76
> Tasks: 154 total, 6 running, 148 sleeping, 0 stopped, 0 zombie
> Cpu(s): 30.7%us, 49.2%sy, 0.0%ni, 11.7%id, 1.3%wa, 1.0%hi, 6.1%si,
> 0.0%st
>
> PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+
> COMMAND
> 26926 postfix 20 0 5840 2552 1792 R 43 0.3 276:51.22 qmgr
>
>
> The problem was never appeared in those machines until, yesterday, I
> added the following to postfix configuration:
>
> #### /etc/postfix/master.cf
> slow unix - - - - - smtp
> -o syslog_name=postfix-slow
>
>
> #### /etc/postfix/main.cf
> # Special "slow" transport:
> slow_destination_recipient_limit=1
> slow_destination_concurrency_limit=1
> slow_destination_rate_delay=5

OK, leave the above settings and see if this helps (Postfix 2.5 or later).

I have not been able to reproduce the problem, but there was
some bogosity with the handling of _destination_rate_delay.

The only reason I know for lots of qmgr CPU usage is when all
mail is being delivered to a "discard" transport. When all mail
is bounced or deferred you'd have lots of disk activity that
causes qmgr to be slowed down.

        Wietse

diff --exclude=man --exclude=html --exclude=README_FILES --exclude=.indent.pro --exclude=Makefile.in -cr src/qmgr/qmgr_entry.c- src/qmgr/qmgr_entry.c
*** src/qmgr/qmgr_entry.c- Fri Dec 14 17:47:21 2007
--- src/qmgr/qmgr_entry.c Wed Mar 4 16:04:21 2009
***************
*** 299,304 ****
--- 299,317 ----
      }
  
      /*
+ * Suspend a rate-limited queue, so that mail trickles out.
+ */
+ if (which == QMGR_QUEUE_BUSY && transport->rate_delay > 0) {
+ if (queue->window > 1)
+ msg_panic("%s: queue %s/%s: window %d > 1 on rate-limited service",
+ myname, transport->name, queue->name, queue->window);
+ if (QMGR_QUEUE_THROTTLED(queue)) /* XXX */
+ qmgr_queue_unthrottle(queue);
+ if (QMGR_QUEUE_READY(queue))
+ qmgr_queue_suspend(queue, transport->rate_delay);
+ }
+
+ /*
       * If the queue was blocking some of the jobs on the job list, check if
       * the concurrency limit has lifted. If there are still some pending
       * deliveries, give it a try and unmark all transport blockers at once.
***************
*** 336,354 ****
       */
      if (which == QMGR_QUEUE_BUSY)
          queue->last_done = event_time();
-
- /*
- * Suspend a rate-limited queue, so that mail trickles out.
- */
- if (which == QMGR_QUEUE_BUSY && transport->rate_delay > 0) {
- if (queue->window > 1)
- msg_panic("%s: queue %s/%s: window %d > 1 on rate-limited service",
- myname, transport->name, queue->name, queue->window);
- if (QMGR_QUEUE_THROTTLED(queue)) /* XXX */
- qmgr_queue_unthrottle(queue);
- if (QMGR_QUEUE_READY(queue))
- qmgr_queue_suspend(queue, transport->rate_delay);
- }
  
      /*
       * When the in-core queue for this site is empty and when this site is
--- 349,354 ----

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